A spectral model in which the nonlinear terms in the governing equations are computed in physical space. Thus, for every model time step, some fields must be transformed to physical space where nonlinear terms are computed and then transformed back to spectral space where they can be applied. These nonlinear terms may consist of advection terms, pressure gradient terms, and energy conversion terms, as well as parameterized physics terms. This is the most common kind of spectral model, as it avoids the expensive computation of interactions among modes in spectral space.